Combined Use of Graphical and Statistical Approaches for Analyzing Historical Precipitation Changes in the Black Sea Region of Turkey
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Date
2020
Journal Title
Journal ISSN
Volume Title
Publisher
Water
Abstract
Many statistical methods have been developed and used over time to analyze historical
changes in hydrological time series, given the socioeconomic consequences of the changes in the water
cycle components. The classical statistical methods, however, rely on many assumptions on the time
series to be examined such as the normality, temporal and spatial independency and the constancy of
the data distribution over time. When the assumptions are not fulfilled by the data, test results are
not reliable. One way to relax these cumbersome assumptions and credibilize the results of statistical
approaches is to make a combined use of graphical and statistical methods. To this end, two graphical
methods of the refined cumulative sum of the di erence between exceedance and non-exceedance
counts of data points (CSD) and innovative trend analyses (ITA)-change boxes alongside the classical
statistical Mann–Kendall (MK) method are used to analyze historical precipitation changes at
16 stations during 1960–2015 in the Black Sea region of Turkey. The results show a good match
between the results of the graphical and statistical methods. The graphical CSD and ITA methods,
however, are able to identify the hidden trends in the precipitation time series that cannot be detected
using the statistical MK method.
Description
Keywords
Hydrometeorological time series, Temporal changes, Significance testing, Classical trend tests, Graphically-oriented trend diagnosis
Citation
Cengiz, T. M., Tabari, H., Onyutha, C., & Kisi, O. (2020). Combined use of graphical and statistical approaches for analyzing historical precipitation changes in the Black Sea region of Turkey. Water, 12(3), 705. doi:10.3390/w12030705